Elektro-Automatik EL 9000 B Slave serie Betriebsanleitung Seite 78

3.7.2.7 Alarms and other problem situations
Master-slave operation, due to the connection of multiple units and their interaction, can cause additional problem
situations which do not occur when operating individual units. For such occurrences the following regulations have
been defined:
• If the DC part of one or more slave units is switched off due to defect, overheating etc., the whole MS system
shuts down the power input and human interaction is required
• If one or more slave units are cut from AC supply (power switch, blackout, supply undervoltage) while the master
is still running and they come back later, they're not automatically initialised and included again in the MS system.
Then the initialisation has to be repeated.
• If the DC input of the master unit is switched off due to a defect or overheating, then the total master-slave system
can take no input power and the DC input of all slaves is automatically switched off, too.
• If the master unit is switched off on the AC side (power switch, supply undervoltage) and comes back later, it
will automatically initialise the MS system again, finding and integrating all active slaves. In this case, MS can
be restored automatically.
• If accidentally multiple or no units are defined as master the master-slave system cannot be initialised.
In situations where one or multiple units generate a device alarm like OV, PF or OT following applies:
• Any alarm of a slave is indicated on the slave's control panel (LED "Error") and on the master's display
• If multiple alarms happen simultaneously, the master only indicates the most recent one. In this case, the particular
alarms can be read from the slave units via USB port. This also applies to remote control or remote supervision,
because the master can only report the most recent alarm.
• All units in the MS system supervise their own values regarding overvoltage, overcurrent and overpower and
in case of alarm they report the alarm to the master. In situations where the current is probably not balanced
between the units, it can occur that one unit generates an OC alarm though the global OC limit of the MS system
was not reached. The same can occur with the OP alarm.
3.7.2.8 Important to know
In case one or several units of a parallel system are not going to be used and remain switched
off, depending on the number of active units and the dynamics of the operation it may become
necessary to disconnect the inactive units from the Share bus, because even when not powered
the units can have a negative impact on the Share bus due to their impedance.
EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
EL 9000 B Slave Series
www.elektroautomatik.de
ea1974@elektroautomatik.de
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